ez-ipupdate: Add Namecheap dynamic DNS support

This does not include any web interface changes.

Namecheap login works a little differently than other dynamic DNS
services. Namecheap only requires the subdomain, domain and a
randomly generated password. These are roughly equivelent to other
services host, username and password, respectively.

Examples:
Update 'www.example.com'
ez-ipupdate -S namecheap -h www -u example.com:e747d77054a844409c486973cb
Update 'example.com'
ez-ipupdate -S namecheap -h @ -u example.com:e747d77054a844409c486973cb

It is unclear if Namecheap supports updating wildcard addresses with
this method, at this time. Support for wildcards will be added if they
are supported by Namecheap.
Web interface: Add Namecheap dynamic DNS support

The subdomain (or @ for the root domain) goes in the Host Name field.
The domain goes in User Name/Email Address field.
The passkey provided by Namecheap goes in the Password/DDNS Key field.

Wildcard is currently unavailable.
Unused by our supported routers
Cleanup: removed modules we don't use (Ralink or obsolete)
Merge branch 'master' of github.com:RMerl/asuswrt-merlin
Bumped revision to 374.35 alpha 1
Merged with 374_306 (minus OpenVPN webui)
Missed in 374_306 merge
Put the new stuff on a diet - stripping compiled binaries
ovpn: missed in the 374_306 merge
vpn: Take Asus's combined PPTP/OpenVPN server config page, re-implemented support for dual OpenVPN server instances"
ovpn: Implement option to enable/disable username-based authentication.

This way, users who flash a FW with Asus's OpenVPN implementation won't lose their existing certificate-based authentication.
Users will retain full control over whether to use username/password based authentication or not.
ovpn: Take Asus's combined PPTP/OpenVPN basic setup, implement instance selection; Add webui option to enable/disable username/password based authentication.
ovpn: typo
ovpn: Fix key/crt decoding on webui; bumped max length back to 3499
webui: Replaced 'certification' with 'certificates'
ovpn: Integrated client key/certs into client config page; unlinked combined key/crt page from webui
avahi: Updated autoconf files
Doesn't fix it, and I don't know enough about autoconf to fix it.  Current workaround is to retry compiling.
Revert "avahi: Updated autoconf files"

This reverts commit b68aa64e994dafb60cb407be24341b9cdb30b551.
ovpn: Fixed crt/key saving on client page